Matrix scaffolding for stem cell guidance toward skeletal muscle tissue engineering
OBJECTIVE To investigate an optimal method for SD rat skeletal muscle decellularization. METHODS Sixteen SD rats (male and female) weighing 180-200 g were used. Thirty-six skeletal muscle bundles obtained from 10 rats were randomly divided into 3 groups: normal group (group A, n=4) received non-decellularization; time group (group T, n=16) and concentration group (group C, n=16) underwent decellularization using hypotonic-detergent method. Concentration of sodium dodecyl sulfate (SDS) was 1.0% for T group, which was subdivided into groups T1, T2, T3 and T4 (n=4 per subgroup) according to different processing durations (24, 48, 72 and 96 hours). Group C was treated for 48 hours and subdivided into groups C1, C2, C3 and C4 (n=4 per subgroup) according to different SDS concentrations (0.5%, 1.0%, 1.5% and 2.0%). The muscle bundles of each group underwent HE staining observation and hydroxyproline content detection in order to get the optimal decellularization condition. Seven of 14 complete skeletal muscle bundles obtained from 6 SD rats were treated with the optimal decellularization condition (experimental group), and the rest 7 muscle bundles served as normal control (control group). The muscle bundles of each group were evaluated with gross observation, Masson staining and biomechanical test. RESULTS HE staining: there was no significant difference between groups T1, T2, C1, C2 and C3 and group A in terms of muscle fiber; portion of muscle fibers in group C4 were removed; muscle fibers in group T3 were fully removed with a complete basement membrane structure; muscle fibers of group T4 were fully removed, and the structure of basement membrane was partly damaged. Hydroxyproline content detection: there was no significant difference between group A and groups C1, C2, C3, T1 and T2 (P > 0.05); significant difference was evident between group A and groups C4, T3 and T4 (P < 0.05); the difference between group C4 and groups T3 and T4 was significant (P < 0.05); no significant difference was evident between group T3 and group T4 (P > 0.05). The optimal decellularization condition was 4 degrees C, 1.0% SDS and 72 hours according to the results of HE staining and hydroxyproline content detection. Gross observation: the muscle bundles of the experimental group were pallid, half-transparent and fluffier comparing with the control group. Masson staining observation: the collagen fibers of the experimental group had a good continuity, and were fluffier comparing with control group. Biomechanics test: the maximum breaking load of the experimental group and the control group was (1.38 +/- 0.35) N and (1.98 +/- 0.77) N, respectively; the maximum extension displacement of the experimental group and the control group was (3.19 +/- 3.23) mm and (3.56 +/- 2.17) mm, respectively; there were no significant differences between two groups (P > 0.05). CONCLUSION Acellular matrix with intact ECM and complete removal of muscle fibers can be obtained by oscillatory treatment of rat skeletal muscle at 4 degrees C with 1% SDS for 72 hours.